1. Field of the Invention
The present invention relates to a plasma processing method and a plasma processing apparatus used for manufacturing a color filter or the like, and more particularly, relates to a plasma processing method and a plasma processing apparatus in which first and second electrodes are disposed oppositely to each other and an object to be processed is processed by a plasma discharge generated between these first and second electrodes.
2. Related Art
Generally, as means for manufacturing a color filter at low cost, an ink-jet method is provided. At the time of manufacturing the color filter by this ink-jet method, it is inevitable to form affinity pattern and non-affinity pattern with respect to an ink (called hereinlater affinity/non-affinity ink pattern).
That is, as shown in FIG. 4A, the color filter is provided with a glass base or substrate 1 as a base member and a black matrix 2 formed on the glass substrate 1 as a partitioning member. The black matrix 2 includes a number of fine concave portions 3, and coloring inks 4R, 4G and 4B for RGB (Red, Green and Blue) fill each of the corresponding concave portions 3, whereby the respective pixels for RGB are formed on the glass substrate 1.
As a method of manufacturing such color filter, there has been conventionally used a pigment dispersion method or the like in which a photolithography process is repeatedly performed for several times. In recent years, however, an ink-jet apparatus has been used for manufacturing the color filter. The manufacturing method using the ink-jet apparatus comprises the steps of forming the black matrix 2 on the glass substrate 1, moving a scanning head of the ink-jet apparatus so as to scan a surface of the glass substrate 1, spraying micro droplets of the coloring inks 4R, 4G and 4B for RGB colors, and charging (filling) the coloring inks 4R, 4G and 4B into the respective concave portions 3 of the black matrix 2 to thereby form the respective pixels for RGB colors on the glass substrate 1 as shown in FIG. 4A.
However, due to differences in properties of the black matrix, the coloring inks 4R, 4G and 4B and the glass substrate 1, there is caused a case where, for example, the coloring inks 4R, 4G and 4B do not correctly fill the concave portions 3 of the black matrix 2 as shown in FIG. 4B. If this coloring ink 4 is for R and B colors, portions lacking the R and B colors are revealed as white voids on a display using this color filter. Further, as shown in FIG. 4C, there is caused a case where the coloring inks 4R and 4B are mutually mixed to each other at a portion between adjacent concave portions 3, 3 of the black matrix 2. In this case, colors are mixed on the display, and the correct colors cannot be displayed.
In order to prevent the above defects such as white voids, the color mixing and the like, there has been proposed a countermeasure in which the glass substrate 1 formed with the black matrix 2 is subjected to a plasma processing as proposed in, for example, Japanese Patent No. 3328297 (Patent Publication 1). In this countermeasure, an organic material is contained in the black matrix 2, and the plasma processing is performed to the glass substrate 1 from an upper surface side of the black matrix 2 under a condition that a degree of non-affinity of the coloring inks with respect to the surface of the black matrix 2 (bank) becomes higher than that with respect to the surface of the glass substrate 1.
FIG. 5 shows a atmospheric pressure plasma apparatus as a conventional apparatus for processing surface of a base substrate having a large surface area by means of plasma processing.
This atmospheric pressure plasma apparatus is provided with, as shown in FIG. 5, a stage electrode 5 on both sides of which insulating layers 6 are arranged. The glass substrate 1 is disposed on the stage electrode 5 and the insulating layers 6, and above the glass substrate 1, a head electrode 7 movable in an arrowed direction is disposed so as to face the stage electrode 5. A process gas is introduced between the stage electrode 5 and the head electrode 7 and a predetermined voltage from an A.C. source is applied therebetween.
The affinity/non-affinity ink pattern is formed on the glass substrate 1 by the plasma discharge generated between the head electrode 7 and the stage electrode 5 while moving the head electrode in the arrowed direction in parallel with the stage electrode 5 and the glass substrate 1. According to this operation, the degree of non-affinity with respect to the ink of the black matrix 2 is increased, and as a result, when the coloring inks for the respective pixels are sprayed to the glass substrate 1 by using an ink-jet printing method at a subsequent manufacturing step, the disadvantages or defects as indicated in FIGS. 4B and 4C can be eliminated, and as shown in FIG. 4A, the ink suitably fills all the concave portions 3.
On the other hand, in the atmospheric pressure plasma apparatus shown in FIG. 5, the stage electrode 5 has a surface area smaller than that of the glass substrate 1 for the reason that, if the stage electrode 5 has an area larger than that of the glass substrate 1, the stage electrode 5 is exposed outward and directly faces the head electrode 7, thereby generating an abnormal discharge such as arc discharge.
Further, Japanese Unexamined Application Publication No. 2002-320845 (JP-A 2002-320845: Patent Publication 2) shows an example of such atmospheric pressure plasma apparatus, in which at least one surface of one of a pair of opposing electrodes is covered with a solid dielectric material, and an upper electrode is formed as a small-size electrode while a lower electrode is formed as a large-size electrode.
However, in the atmospheric pressure plasma apparatus described above and shown in FIG. 5, the stage electrode 5 has the area smaller than that of the glass substrate 1, so that the plasma discharge cannot be sufficiently performed at a peripheral portion, and particularly, processing final end side, of the glass substrate 1. Because of this reason, on the processing final end side, the non-affinity of the black matrix 2 with respect to the ink becomes extremely inadequate, and hence, a desired surface processing is not performed. As a result, in the case where the color filter is manufactured by the ink-jet method, a white void or color mixing is caused on the display, resulting in undesirable color display of defective quality.
In addition, as other method, there may be provided a plasma spraying method for spraying the plasma onto the glass substrate 1. By this method, however, low processing ability and insufficient surface processing ability are provided.
Furthermore, in the invention disclosed in the above Patent Publication 2, although the lower electrode has the area larger than that of the upper electrode and an abnormal discharge such as arc discharge is caused, it is considered that the generation of such abnormal discharge is avoided by widening a distance between the electrodes. However, in the case of widening the distance between the electrodes, there is posed a problem such that a sufficient surface processing function cannot be achieved.
Still furthermore, in the invention also disclosed in the Patent Publication 2, if a defect such as pin-hole is caused to the solid dielectric material disposed on at least one surface of the paired opposing electrodes, there is a possibility of generating an abnormal discharge, which may provide an undesirable problem.